The Intersection of Ethnicity, Class, Gender and Geography in Preventable Mortality Using Four Decades of National Data.

This study uses national-level census and mortality data to investigate the changing social class and ethnic patterns in premature mortality in New Zealand from 1975 to 2014. During this period there was a political struggle for recognition of indigenous rights, a social policy focus on inequality, and major macro-economic reform. A novel web-based inequality visualiser was created to enable statistically robust and user defined exploration of mortality inequalities using otherwise confidential data.

We used three different approaches to inequalities in mortality using data for the entire country. Firstly we repeated previous studies for the periods 1975-1977, 1985-87 and 1995-1997 to include 2005-2007 and 2012-2014. This involved national death registration data for each period and the five yearly national population censuses from 1976 to 2013 to examine changing patterns in social class differences in all cause, preventable, and non-preventable mortality for indigenous Maori and non-Maori men under the age of 65. Mortality data were obtained from the national mortality data collection – this included occupational information that was used to classify individual into occupationally derived social classes. Secondly we explored changing patterns of mortality inequality using annual mortality records for the period 1988 to 2014 for both males and females for all ethnicities by socio-economic position (SEP) using a small area social deprivation measure. Thirdly we created a data visualiser using R and R-Shiny to enable user-defined explorations of inequality using otherwise publicly inaccessible official data.

Social class and ethnic differences in mortality have increased since 1975. There are significant persistent inter-ethnic disparities within each social class for preventable, non-preventable and all causes of mortality. There are also increasing intra-ethnic social class differences in mortality. The persistently high inequality in preventable deaths indicates that New Zealand’s government-funded health sector is still not meeting the health needs of minorities and low-SEP people.